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A Sunshade In Space To Combat Global Warming
ultracool writes, "While the only permanent solution for human-driven global warming is developing renewable energy, a temporary hack to counteract possible abrupt climate change is to build a giant sunshade in space. The sunshade would be launched in small pieces by electromagnetic launchers, conventional chemical rockets being far too expensive. The sunshade could be developed and deployed in 25 years, would last about 50 years, and would reduce the amount of sunlight reaching Earth by 2% — enough to balance heating due to a doubling of carbon dioxide in the atmosphere." From the article: "The [trillions of] spacecraft would form a long, cylindrical cloud with a diameter about half that of Earth, and about 10 times longer... Sunlight passing through the 60,000-mile length of the cloud, pointing lengthwise between the Earth and the sun [at L-1], would be diverted away from our planet... The sunshade could be deployed by a total 20 electromagnetic launchers [collectively] launching a stack of [a million] fliers every 5 minutes for 10 years."
Um...
/., actually) that they did a study and the amount of sunlight that actually reaches the surface of the earth has decreased by a whopping 10% since 1950. That alone puts a pretty huge dent in your theory. This is probably due to the fact that...
1. I'm pretty sure that I read (on
2. Life forms are surprisingly adaptive. You act as if plants are completely helpless in the face of a minor 2% change. I'm not saying there wouldn't be some long-term consequences (more to do with specific species thriving/suffering as opposed to planet-wide climate change) , but a permanent, perfectly linear/proportional drop in oxygen output is unrealistic.
3. Sunlight is only the energy source--plenty of other factors are involved in oxygen production.
4. I'm not at all sure that the greenhouse effect depends on gas proportions. You imply that the overall level of greenhouse gases could stay the same but if the relative amounts of other gases dropped, we would warm up. That's entirely possible, but that's not how I assumed it worked. Mars is pretty cold, and its thin atmosphere is composed (IIRC) mostly of CO2, so that seems to be another dent in your theory. Venus, on the other hand, has an extremely thick atmosphere of C02 and it's hotter than Mercury. From this, I would hazard a guess that raw quantities of greenhouse gasses are more important than percentages.
5. Even if greenhouse gases did have a proportional effect, the missing oxygen might very well be replaced by other inert gases. Plants aren't simple oxygen machines; they give and take in ways that I simply cannot recall (nor be bothered to Google) at 5:30 AM.
Oh, and personal responsibility doesn't work. Sorry. Wish it did... but it doesn't, so let's not completely neglect the worst-case-scenario plans, eh?